Carbon, nitrogen, and phosphorus distribution in particle size-fractionated separated pig and cattle slurry

Solid liquid separation of animal slurry is a method to reduce the excess nutrient loads from intensive livestock production. Five different separation technologies (sedimentation, centrifugation, pressurized filtration, polymer flocculation and drainage, and iron chloride addition + polymer flocculation and drainage) were applied to pig and cattle slurry in a laboratory study. Separation efficiencies of mass, dry matter (DM), N, and P were measured. Particle size fractionation of the solid fractions was performed by subjecting them to wet fractionation and C, organic N (N(org)), and P contents were subsequently measured. Chemical pretreatment with polymer before gravity drainage separated DM, total N, and P from raw pig and cattle slurry with the highest efficiencies. Sedimentation and centrifugation separated P from pig and cattle slurries with higher simple separation efficiencies (0.77 and 0.70, respectively) compared with pressurized filtration (0.15 and 0.37). Pressurized filtration transferred the lowest masses (14 and 18%) to the solid fractions. Solid fractions from pig slurry generally contained higher concentrations of P and C compared with cattle slurry solid fractions. The majority of C in solid fractions was present in particles > 25 microm, whereas N and P were present in larger proportions in particles < 25 microm. Chemical pretreatment increased the capture of smaller N(org)- and P-rich particles into larger particles between 25 and 1000 microm.     

No evidence for offspring sex-ratio adjustment to social or environmental conditions in cooperatively breeding purple-crowned fairy-wrens

When fitness returns or production costs vary between male and female offspring, selection is expected to favor females that adjust offspring sex ratio accordingly. However, to what extent vertebrates can do so is the subject of ongoing debate. Here, we explore primary sex ratios in 125 broods of cooperatively breeding purple-crowned fairy-wrens Malurus coronatus. We expected that females might adjust offspring sex ratio because this passerine species experiences considerable variation in social and environmental conditions. (1) However, although helpers substantially increase parental fitness, females (particularly in pairs and small groups) did not overproduce philopatric males (helper-repayment hypothesis). (2) Sex-ratio adjustment based on competition among individuals (helper-competition hypothesis) did not conceal helper-repayment effects or drive sex allocation on its own: while high-quality territories can accommodate more birds, brood sex ratios were independent of territory quality, alone or in interaction with group size. (3) Additionally, males are larger than females and are possibly more costly to produce (costly sex hypothesis), and (4) female offspring may benefit more from long-term effects of favorable conditions early in life (Trivers–Willard hypothesis). Nonetheless, large seasonal variation in food abundance was not associated with a consistent skew in primary sex ratios. Thus, overall, our results did not support the main hypotheses of adaptive sex-ratio adjustment in M. coronatus. We discuss that long-term differential costs and benefits may be insufficient to drive evolution of primary sex-ratio manipulation by M. coronatus females. More investigation is therefore needed to determine the general required sex differences in long-term fitness returns for mechanisms of primary sex-ratio manipulation to evolve.     

淋洗剂对多金属污染尾矿土壤的修复效应及技术研究

以我国南方某多金属复合污染尾矿土壤为研究对象,对土壤中重金属全量和各形态含量进行分析.通过系列振荡淋洗试验研究了蒸馏水、草酸、柠檬酸、乙酸、硝酸和EDTA对污染土壤的淋洗效果,筛选合适的淋洗剂及其最佳的液土比、液洗时间、淋洗次数等技术参数,并提出利用综合毒性消减指数来综合评价淋洗剂对污染土壤的修复效果.结果表明,该土壤以Cd和Pb污染最为严重,含量分别达52.2 mg.kg-1和4 836.5 mg.kg-1;淋洗剂对土壤中不同重金属元素的淋洗效果差异明显,其中对Cr的去除率最高仅为2.7%,而最多能去除约60%的Cd和Pb;蒸馏水对重金属几乎没有脱除效果,去除率都在0.1%以下,草酸和乙酸对重金属的去除率也较低,0.1 mol.L-1的EDTA是适合的高效淋洗剂;基于综合毒性消减指数和经济成本,选择在1∶6土水比2次淋洗3 h的技术条件.     

Approaches to correct for double counting in tiered hybrid life cycle inventories

This paper presents an approach for inventory compilation and adjustment of double counting in tiered hybrid life cycle inventories (LCIs). The combination of input–output and physical inventory data on coefficient level is a convenient way of constructing a hybrid LCI that has both good detail and completeness. The proposed approach formalizes how to deal with partially overlapping data in inventory compilation. This particular approach requires that the issue of double counting is resolved in a consistent manner. Algorithms for identifying and adjusting for double counting are developed. Identification is performed based on a structural path analysis (SPA). Two algorithms for adjustment are presented. The first method is relatively simple to implement but has limitations to its applicability when performing a detailed assessment. The second method is more complex to implement but provides results that allow for more comprehensive structural inventory analysis. Numerical examples are provided in Appendix.     

RUNOFF SIMULATION USING RADAR RAINFALL DATA1

ABSTRACT: Rainfall data products generated with the national network of WSR-88D radars are an important new data source provided by the National Weather Service. Radar-based data include rainfall depth on an hourly basis for grid cells that are nominally 4 km square. The availability of such data enables application of improved techniques for rainfall-runoff simulation. A simple quasi-distributed approach that applies a linear runoff transform to grid-ded rainfall excess has been developed. The approach is an adaptation of the Clark conceptual runoff model, which employs translation and linear storage. Data development for, and results of, an initial application to a 4160 km² watershed in the Midwestern U.S. are illustrated.     

Part-time versus full-time employment status differences: A replication and extension

Two groups of part-time employees were compared to full-time employees on several organizationally relevant reactions and behaviours in order to replicate and extend research on potential employment status differences. After controlling for demographics, it was found that there were mean differences between the groups; however, no evidence was found for differences in how the various groups ‘process’ organizational experience. Based on the results, implications for managing part-versus full-time employees are discussed.